地物化方法在航磁异常查证中的应用

航磁异常查证是矿产勘查中的一个重要环节,其目的是通过地面查证,确定异常是否存在,追踪异常源,了解异常源所处的地质环境,对异常作出客观评价,提出进一步工作的建议,为后续资料解释提供依据.通过使用地物化综合方法对黑C-2011-02243号异常查证发现：地质剖面测量和土壤地球化学测量可在地表发现较好的找矿线索;高精度磁测及激电中梯测量则反映了深部地质体及矿化特征.依据查证结果认为,在进行航磁异常查证工作时,可优先进行剖面性的地质、高精度磁法及土壤地球化学测量工作;在分析上述测量结果的基础上安排剖面性的电法测量;如存在进一步找矿信息,可安排面积性物化探测量及工程验证工作.     

祁连山新元古代——早古生代火山作用与铁-铜多金属成矿

祁连山造山带新元古代—早古生代是板块构造演化与成矿的最重要时段,铁、铜多金属矿产资源丰富,成矿作用与新元古代—早古生代火山作用密切相关。根据矿床产出构造位置,将祁连山铁、铜多金属矿床分为4类:大陆裂谷型铁(铜)矿床、岛弧-岛弧裂谷型铜多金属矿床、陆缘裂谷型铜多金属矿床、扩张脊型铜矿床。镜铁山铁(铜)型矿床是新元古代大陆裂谷火山作用过程中热水沉积作用的产物;东沟铜矿为晚寒武世大洋扩张脊火山作用的产物;白银矿田铜多属矿床是奥陶纪与岛弧-岛弧裂谷火山作用的产物;石居里铜矿是晚奥陶纪弧后扩张脊有关火山作用的产物;红沟铜矿则是晚奥陶世陆缘裂谷火山作用的产物。     

Using climate to relate water discharge and area in modern and ancient catchments

Models relating sediment supply to catchment properties are important in order to use the geological record to deduce landscape evolution and interplay between tectonics and climate. Water discharge (Q _w) is an important factor in the widely used ‘BQART ’ model, which relates sediment load to a set of measurable catchment parameters. Although many of the factors in this equation may be independently estimated with some degree of certainty in ancient systems, water discharge (Q _w) certainly cannot. An analysis of a world database of modern catchments with 1255 entries shows that the commonly applied equation relating catchment area (A ) to water discharge (Q _w = 0·075A^0·8) does not predict water discharge from catchment area well in many cases (R ² = 0·5 and an error spanning about three orders of magnitude). This is because the method does not incorporate the effect of arid and wet climate on river water discharge. The inclusion of climate data into such estimations is an opportunity to refine these estimates, because generalized estimates of palaeoclimate can often be deduced on the basis of sedimentological data such as palaeosol types, mineralogy and palaeohydraulics. This paper investigates how the relationship between catchment area and river discharge varies with four runoff categories (arid, semi‐arid, humid and wet), which are recognizable in the geological record, and modifies the coefficient and exponent of the above‐mentioned equation according to these classes. This modified model yields improved results in relating discharge to catchment area (R ² = 0·95 and error spanning one order of magnitude) when core, outcrop or regional palaeoclimate reconstruction data are available in non‐arid systems. Arid systems have an inherently variable water discharge, and catchment area is less important as a control due to downstream losses. The model here is sufficient for many geological applications and makes it possible to include variations in catchment humidity in mass‐flux estimates in ancient settings.     

高寒区抽水融冰渠道水温沿程衰减规律——以红山嘴水电站为例

抽水融冰技术是解决高寒区引水式电站冬季运行冰害问题的有效措施之一。为研究抽水融冰对电站引水渠道冬季引水的水温控制规律,以红山嘴水电站为例,基于RNG κ-ε模型数值模拟研究结果,从热流量比角度探讨了渠道水温沿程衰减规律,并采用2013年2月和2014年1月原型观测结果进行了验证。结果表明:渠道水温沿程衰减过程可分为骤降段、过渡段和缓降段3部分,各段范围受外界条件控制;衰减曲线呈幂函数分布,相关系数达到98%;对比气温对渠温沿程衰减的影响表明,随着大气温度的降低,渠道水温沿程衰减速度明显加快;-10 ℃为水温衰减过程变化转折点,当气温高于-10 ℃时,可以近似认为渠温衰减规律一致,渠温沿程变化主要受到热流量比值影响;低于-10 ℃时,气温对渠道水温沿程变化影响显著。     

羌塘地块西南缘上侏罗统-下白垩统海相地层的发现

通过1∶5万区域地质调查,在青藏高原羌塘地块西南缘鸡夯地区原划上三叠统日干配错群中新识别出一套上侏罗统—下白垩统地层。本文根据该套地层的岩石组合以及古生物面貌特征,初步探讨了该套地层的沉积环境和沉积相特征,对其中发育的玄武岩夹层采用锆石U-Pb(LA-ICP-MS)同位素测年方法,获得其年龄为118.3±2.1Ma。在发育的生物碎屑灰岩夹层中采集了珊瑚、双壳类、腕足、腹足类化石,化石资料显示该套地层形成于晚侏罗世—早白垩世。这是首次在南羌塘地块发现该时期海相地层,这一发现证明南羌塘地块在晚侏罗世—早白垩世时期海水并未完全退出,而是局部发育海相三角洲。     

关于《中国扬子区兰多维列统特列奇阶及其与英国的对比》一书若干问题的商榷

《中国扬子区兰多维列统特列奇阶及其与英国的对比》一书（陈旭,戎嘉余,1996）有以下结论：①将回星哨组、茅山组、西坑组等的层位归属于特列奇阶上部;②将回星哨组、茅山组及其相当地层与英国特列奇阶对比;③将扬子区特列奇阶的顶界置于回星哨组、茅山组及其相当地层之顶;④将回星哨组、茅山组、西坑组等地层资料编制的古地理图称为特列奇期晚期古地理图;⑤将回星哨组、茅山组、西坑组等地层与上覆中泥盆统—中二叠统之间的不整合面代表的上升运动,称为“特列奇期的扬子上升”。笔者等依据多年对扬子地台志留纪地层剖面的实地考察和近数十年来扬子区坟头组中—上部、茅山组、回星哨组、小溪峪组、西坑组等地层中文洛克世、拉德洛世、普里多利世早期古生物化石的发现,认为：①回星哨组、小溪峪组、茅山组、西坑组等的层位是文洛克统—普里多利统;② 回星哨组、小溪峪组等大致与英国的文洛克统—普里多利统对比;③回星哨组、小溪峪组、茅山组的顶界是文洛克统—普里多利统剥蚀后残留的层位随地而异的顶界;④根据回星哨组、西坑组、茅山组等地层资料编制的古地理图应是文洛克世—普里多利世古地理图;⑤“扬子地台整个上升”（黄汲清,1945）的时代是志留纪末期,没有“特列奇期的扬子上升”。特提出商榷。上述这些地层时代的解决,对扬子区志留系4统层序的建立具有重要意义,而且也为中国扬子区与英国命名剖面志留系的对比以及中国南方早古生代加里东运动最后一幕时代的再次确定提供了地层学和古生物方面的依据。     

砾石在分析盆地物源区迁移与湖岸线演化中的作用*

中国中西部盆地的盆山结合部位,勘探程度较低、钻井少、地震成像复杂,致使利用传统的地震相、测井相、岩心资料等研究原型盆地岩相古地理特征较为困难。基于露头中巨厚砾岩发育层段对应盆地内储集层平面展布范围最广这一认识,运用“将今论古”方法,建立南天山前现代冲积扇、扇三角洲平原、河流等沉积体系中砾石与搬运距离关系,以及不同沉积相类型中砾石发育产状与湖岸线远近关系,定量计算了准噶尔盆地多条重点剖面侏罗系—白垩系现今位置与沉积物源区和湖岸线演化的距离,恢复了侏罗纪—白垩纪物源区范围与湖岸线演化过程。认为侏罗纪—早白垩世砂砾岩储集体向盆地内延伸范围最大时期的湖岸线,明显与现今盆地边缘线有一向西北方向敞开的夹角,该认识对在编制岩相古地理图过程中以盆地边缘线即为湖岸线的观念提出了不同见解,为恢复准南等低勘探程度区原型盆地的岩相古地理特征、预测有利储集体的展布提供参数依据。建立的刻画物源区变化和湖岸线迁移的定量评价方法与参数,是对传统沉积学研究的有益补充。     

Including animal to plant protein shifts in climate change mitigation policy: a proposed three-step strategy

Strong and rapid greenhouse gas (GHG) emission reductions, far beyond those currently committed to, are required to meet the goals of the Paris Agreement. This allows no sector to maintain business as usual practices, while application of the precautionary principle requires avoiding a reliance on negative emission technologies. Animal to plant-sourced protein shifts offer substantial potential for GHG emission reductions. Unabated, the livestock sector could take between 37% and 49% of the GHG budget allowable under the 2°C and 1.5°C targets, respectively, by 2030. Inaction in the livestock sector would require substantial GHG reductions, far beyond what are planned or realistic, from other sectors. This outlook article outlines why animal to plant-sourced protein shifts should be taken up by the Conference of the Parties (COP), and how they could feature as part of countries’ mitigation commitments under their updated Nationally Determined Contributions (NDCs) to be adopted from 2020 onwards. The proposed framework includes an acknowledgment of ‘peak livestock’, followed by targets for large and rapid reductions in livestock numbers based on a combined ‘worst first’ and ‘best available food’ approach. Adequate support, including climate finance, is needed to facilitate countries in implementing animal to plant-sourced protein shifts.

Key policy insights

• Given the livestock sector’s significant contribution to global GHG emissions and methane dominance, animal to plant protein shifts make a necessary contribution to meeting the Paris temperature goals and reducing warming in the short term, while providing a suite of co-benefits.

• Without action, the livestock sector could take between 37% and 49% of the GHG budget allowable under the 2°C and 1.5°C targets, respectively, by 2030.

• Failure to implement animal to plant protein shifts increases the risk of exceeding temperate goals; requires additional GHG reductions from other sectors; and increases reliance on negative emissions technologies.

• COP 24 is an opportunity to bring animal to plant protein shifts to the climate mitigation table.

• Revised NDCs from 2020 should include animal to plant protein shifts, starting with a declaration of ‘peak livestock’, followed by a ‘worst first’ replacement approach, guided by ‘best available food’.

     

那曲高寒草地总体输送系数及地面热源特征

利用中国科学院那曲高寒气候环境观测研究站那曲/BJ观测点的野外观测数据,估算了青藏高原那曲地区典型高寒草地下垫面的热量和水汽总体输送系数以及地表大气相对湿度因子,在此基础上利用中国气象局那曲气象站1980-2016年的常规业务观测数据,采用总体输送法计算并分析了那曲高寒草地地表通量特征。研究结果表明:(1)那曲/BJ观测点地表大气相对湿度因子γ的数值在33%~62%,9月最大,2月最小,热量和水汽输送系数CH和Cλ的季节变化范围分别在1.6×10^-3~2.7×10^-3和1.0×10^-3~2.0×10^-3,两者存在较大的差异。(2)1980-2016年那曲高寒草地感热通量总体呈现减弱趋势,而潜热通量呈现增强趋势,导致地面热源变化趋势不明显;分阶段来看,感热通量的变化在2004年前后发生转折,转折点前后的趋势为先减弱后增加,潜热通量在1994-2005年下降趋势明显,这也导致地面热源在1995-2005年有一个明显的减少。(3)年内季节变化上潜热通量相较于感热通量更明显,地面热源的季节变化更依赖于潜热通量的季节变化。     

南北带强震年度预测能力估计

对中国地震局原分析预报中心测震学科1988～1999年度划定的南北地震带强震(M≥7)危险区进行了回顾和分析。 结果表明, 从过程角度研究前兆地震活动图像及其演变是年度和中短期强震预测的有效途径, 这为南北地震带强震震情跟踪提供了条件。